1. Field of the Invention
The present invention relates to an air conditioner, and more particularly, to an air conditioner for defrosting an outdoor heat exchanger using hot gas.
2. Description of the Related Art
In general, an air conditioner is an apparatus for cooling or heating indoor using a refrigeration cycle including a compressor, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger. That is, the air conditioner can be formed as a cooler for cooling indoor or as a heater for heating indoor. The air conditioner can be formed as an air conditioner for both cooling and heating for cooling or heating indoor.
When the air conditioner is formed as an air conditioner for both cooling and heating, the air conditioner includes a 4-way valve for changing a flow path of a refrigerant compressed in a compressor according to a cooling operation and a heating operation. That is, when a cooling operation is performed, a refrigerant compressed in the compressor is flowed to an outdoor heat exchanger by passing through a 4-way valve, and the outdoor heat exchanger functions as a condenser. A refrigerant condensed in the outdoor heat exchanger is expanded in the expansion device and is injected into an indoor heat exchanger. In this case, the indoor heat exchanger functions as an evaporator, and a refrigerant evaporated in the indoor heat exchanger is injected into the compressor by passing through again the 4-way valve.
When a heating operation is performed, a refrigerant compressed in the compressor flows to the indoor heat exchanger by passing through the 4-way valve, and the indoor heat exchanger functions as a condenser. A refrigerant condensed in the indoor heat exchanger is expanded in the expansion device and is injected into the outdoor heat exchanger. In this case, the outdoor heat exchanger functions as an evaporator, and a refrigerant evaporated in the outdoor heat exchanger is injected into the compressor by passing through again the 4-way valve.
In such an air conditioner, water is generated on a surface of a heat exchanger acting as an evaporator while operating, and water is generated on the surface of an indoor heat exchanger in a case of a cooling operation and water is generated on a surface of an outdoor heat exchanger in a case of a heating operation. In this case, upon performing a heating operation, when condensed water generated on a surface of the outdoor heat exchanger is frozen, a smooth flow and heat exchange of outdoor air are disturbed, thereby deteriorating heating performance.
Therefore, in order to remove frosted condensate water, when a heating operation is stopped while performing a heating operation and a refrigerating cycle is operated in an inverse cycle (i.e., a cooling operation), a refrigerant of a high temperature and a high pressure passes through the outdoor heat exchanger and frost on a surface of the outdoor heat exchanger is melted by heat of the refrigerant. However, when a defrost operation is performed by the inverse cycle, indoor heating should be stopped.